Food fryer with continuously filtered cooking oil

ABSTRACT

In a deep-fat cooking appliance, a cooking oil circulation system includes a filter assembly which has a disposable porous filter. A motor pump continuously draws oil from a midpoint in a deep cooking well and through the filter. The oil returns to the deep well via a downspout poised above a splash ledge in the deep well so that there is a minimum of agitation in the oil. A clogged filter alarm indicates when the porous material should be replaced.

[ Mar. 14, 1972 [54] FOOD FRYER WITH (IUNTIINUUFUSILY 2,733,815 2/1956Kwochka et a1... ..99/408 UX lFlllLTElRED UUUKKNG OIL 2,652,767 9/1953Childs 1 ..99/408 3,398,673 8/1968 l(oplock..... ...2l/l67 X [72]Inventor. Woliord A. Morris, Springfield, 111. 3,280,722 /1966 Rahauser"99/332 [73] Assignee: Restaurant Products, Inc., Springfield, Ill. ,60110/1963 Longmire ---99/330 3,431,835 3/ 1969 Angold "99/408 [22] Filed:Apr. 22, 1970 2,287,396 6/1942 ROlh .99/403x 211 Appl.N0.: 30,6503,097,589 7/1963 M661 ..99/408 1521 05.111 ,.99/2142,99/337,99/40s, ZETF Q 210/90, 210/167, 210/493, 210/1510. 12 51 1111. cu. "1 1471137112[58] 1 161061961611 ..210/167,90,493,D1G.8; [57] ABSTRACT 99/408 33214034071418 In a deep-fat cooking appliance, a cooking oil circulation 342system includes a filter assembly which has a disposable porous filter.A motor pump continuously draws oil from a [56] References Citedmidpoint in a deep cooking well and through the filter. The oil UNITEDSTATES PATENTS returns to the deep well via a downspout poised aboveasplash ledge 1n the deep well so that there 1s a minimum of agitation3,483,982 12/1969 Nelson ..210/167 in the A clogged fil 1 indicates whenthe porous 2,578,129 12/1951 Daugherty.. .....99/408 materialshould be 13,241,680 3/1966 Humbert ..210/493- 1Cl11uims, 13 Drawing Figures 3/ 1 iW 1' 1 38 11 1 1 111 1' 5 1 i a r 1 WI 26' 111 l 11111, 1 Mi I M Q 1 111 1 11 319 111 1 1 1 MW i I 1 I 1 1 1 k H 1 1 1 1 i 1i 1 E I I 1 i 6 \111 1 E96 111. I 11 11 ,WIMMD QQI 1| 11 1 1 1 36 .1 1 1 1 1 1 2; 1| 1. 1TOSENS213/54 7; 1116 I 1 111 11 5 i 1] 1 3i 57 l 1 1 23 U FOOD IFIWEFWITH CONTINUGIUSLY lFllL'llEItEll) COOKING GIL This invention relates tofood fryer appliances, and more particularly to built-in fryers withcontinuously operating oil circulating and filtering devices.

Deep-fat fried foods are very popular. French-fried potatoes or deepfried chicken are just two examples of the many such fried foods whichcould be cited. Generally speaking, these and similar foods are cookedby being dropped into and covered by boiling oils. The oils enter intoand become part of the food while the heat of the boiling oils cooks thefood.

Even a moments reflection makes it obvious that the quality of thecooking oil is of prime importance. First, human health and well-beingare at stake. The oil must be completely digestible and free of allcontaminants which could endanger the health or well-being of personseating the foods. Second, assuming that there is a completely safe oil,the problems of taste are important. If the oil is rancid, there is notmuch point in deep-fat frying a food in an effort to enhance itsaesthetic taste qualities.

There are still other reasons, not directly related to the foodqualities, for using cooking oil processing appliances. One of thesereasons relates to the need for cleaning the fryer and keeping theplumbing clean and free of grease. Another reason relates to simplicityof operation, low-cost maintenance, and ease of changing filters withouttaking the fryer out of service. Yet another reason for oil processingis to enable reuse of the shortening and, therefore, to cut cookingcosts.

Various commercial products and appliances are presently offered torestaurateurs to enable them to process the cooking oil and therebyimprove the quality and taste of fried foods. For example, smallportable cooking oil processing units may be brought to the largecounter fryers. These units pump the cooking oil in the counter fryersthrough oil filters and strainers which remove acids, odors, generalsediments, and taste residues from previously cooked foods. Generally,they do not process the oil continuously during the cooking. Anotherproblem is that they do not enable the persons who use the processingunit to handle hot oil with a minimum possibility of danger of burningthem.

The foregoing are only a few of the considerations which apply to theuse and design of deep-fat food fryers. Still other considerations willreadily occur to those who are skilled in the art.

Accordingly, an object of the invention is to provide new and improvedcooking oil processing apparatus for food fryers. In this connection, anobject is to provide food fryers having continuously circulating cookingoils, with filtration, throughout the entire cooking cycle. Here, anobject is to provide a cooking oil filtration system having automaticsensing, with alarm means operated when the system requires attention.In greater detail, an object is to sense troubles and give a signal whenthe filter is clogged and must be changed.

Yet another object of the invention is to provide new and improvedcooking oil processing equipment which is easier to operate andmaintain. Here an object is to provide a relatively safe deep-fat fryerwhich may be used and maintained with a minimum danger from splatteringof hot grease, especially while oil is being removed from the fryer. Inthis connection, an object is to enable the oil or filter to be changedwithout interrupting a cooking cycle. In particular, an object is topreclude opening the oil system while it is filled with hot oil.

In keeping with an aspect of the invention, the fryer includes a deepwell for holding and heating the cooking oils as well as receiving acooking basket containing the food to be cooked. A cold oil chamber isprovided at the bottom of a deep cooking container to trap sedimentsuspended in the oil. During cooking, the cooking oil is pumped from apoint above the cold oil chamber (without disturbing the trappedsediment), through a filter for purifying the oil, and back into thedeep well. The filter may take any of several forms such as a pleatedpaper cylinder; however, a preferred embodiment utilizes a cylindricalhousing for receiving a pleated filter paper bag. A pipe carries thecooking oil into the center of the pleated paper cylinder or bag. Then,the oil oozes through the filter paper and flows out into thecylindrical housing from which it is pumped back into the deep well.

The equipment for accomplishing these and other objects will beunderstood best from a study of the following specification and theattached drawings in which:

FIG. It is a perspective view of a floor model deep-fat fryerincorporating the principles of the invention;

FIG. IA shows a motor-pump combination having a pressure or vacuumsensor t hereon;

FIG. 2 is a schematic representation of the housing of FIG.

FIG. 2A shows a downdraft baffle for drawing larger sediment into asettling area of the well;

FIG. 3 is a top plan view of a housing for receiving the filterassembly;

FIG. 2- is a front elevation view of the assembly of FIG. 3 taken alongline 4-d;

FIG. 5 schematically illustrates an interlocking arrangement forpreventing a removal of the filter housing while it is filled with oil;1

FIG. 6 is a side view which shows the latch arrangement controlled bythe handle of FIG. 5;

FIG. 7 is a front view of the latch of FIG. 6 taken along line 7-7ofFIGS. 5 and 6;

FIG. d is a plan view of a first embodiment of a pleated filter paperbag;

FIG. 9 is a side elevation view of the filter of FIG. 8 taken along line99 thereof;

FIG. I0 is a side elevation view of a second embodiment of theinvention; and

FIG. 11 is a perspective view of an open-ended pleated paper cylinderfilter with a suitable compressible ring at each end which seals thefilter against the top and bottom of the filter housing when assembledfor use.

The major assemblies of FIGS. I and 2 comprise a cabinet, support, orhousing 20, a deep well 21 for receiving the cooking oil, a filterassembly 22, and a motor-driven pump assembly 23.

The housing 20 may take any form which is suitable for the intendedenvironment. For example, it could be a simple angle iron stand; or, itcould be made of brushed stainless steel with or without decorative orcolored panels. Preferably, at least one door 24 is provided on one sideof the cabinet in order to give access to the filter assembly 22. Thetop of the cabinet is open to provide access to the deep well 21. Theback of the top includes a splash panel 25 and an assembly (not shown)for pivotally supporting one end of a heating element 26. This way, theelement 26 may be swung upwardly on the pivot to be out of the way forcleaning. The electrical element 26 heats the cooking oil.

The deep well 21 is divided into two parts by a perforated basket orscreen 28 which may be lifted out for easy cleaning. This basket allowsthe larger particles from the cooked foods to fall into an accumulationarea 29 filled with relatively cold oil. Supported on and nesting withinthe strainer element 28 are one or more containers 30, 30 for receivingthe food being cooked. A pair of hangers 31 are provided to support thefood containers above the cooking oil. These hangers may or may not beprovided to support the food containers when they are out of the oil.These hangers may be attachedto a suitable off and on switch 31a forturning off the fryer motor when the food is removed from the oil.

According to the invention, the cooking oil in the well 21 is filteredcontinuously during the cooking process. In greater detail, the space 29beneath the screen 28 forms a sump or chamber for accumulating largefood particles. Projecting above this chamber 29 is an overflow pipe 32.This is important since pump 23 may draw the cooking oil from the spaceabove the screen 28, thus leaving the trapped sediment undisturbed inthe area 29. This way, the larger sediment is prevented from enteringthe filtration system, thereby greatly prolonging the life of thefilter. In another embodiment (FIG. 2A) suitable baffles 32a may beincluded to form a downdraft 3211 which positively pulls larger sedimentparticles from the cooking area and into the chamber 29 before oil 320enters the filter housing. The oil is pumped through the pipe 32, intofilter housing 22, through pipe 36, pump 23, and one or more downspouts38, to the deep well 21.

Means are provided for reintroducing oil into the deep well withoutagitating the oil or washing the food by a swift-flowing stream of oil.More particularly, as best seen in FIG. 2, the downspouts 38 direct theflow of oil onto a ledge 39 in the deep well 21. This ledge actssomewhat as a splash block and somewhat as a deflector. Thus, there is agentle flow of oil back into the well which does not disturb the food inthe containers 30, 30. l-leretofore, the tendency has been to shower thefood with the returning stream of oil, and this adversely affected thecooking. For example, it washed the batter ofi a deep fried meat.

A manual or automatic valve 40 may close off the overflow pipe 32 toretain the cooking oil in the deep well 21 when it is necessary toservice the filtration system. This valve closure causes the pump 23 tocompletely empty the oil from the housing 22 and deposit it in the well21. This emptying enables a disposal and replacement of filter 90,cleaning of the filter housing 22, for example, without stopping thecooking process.

A sensor 41, in pipe 36, detects a pressure change in the oildistribution system, which indicates when a clogged filter is in need ofchanging. An alternative position places the sensor 41a on the pump 23,FIG. 1A. When the sensor 41 is in a posi tion indicating a cloggedfilter, such position is caused by an increased vacuum formed in thepipe 36 responsive to the pump 23 trying to pull the oil, which will notflow through the filter housing 22.

When such increased vacuum occurs, a signal is sent from sensor 41 overa wire (not shown) to light an indicator lamp at 43. The lamp remainslighted until the filter housing 22 is serviced, valve 40 is opened, andoil flow at a proper pressure resumes in the pipe 36. Thereafter, oilpasses freely through the filter housing 22. Since only a normal vacuumbuilds up in the pipe 36, the sensor 41 no longer sends any cloggedfilter alarm signal. The lamp at 43 is again dark. Multicolor lights maybe used in connection with sensor means for detecting degrees ofpressure or vacuum in order to indicate the relative condition of thefilter.

If desired, a suitable drain pipe P (FIG. 1A) may be provided as anoutlet for draining oil from the system. Since it is connected to theoutput side of the pump 23, this pipe enables a forcible power drainingof all oil from the system at high speed. It is not relevant whether theoil is drained into a storage tank T or into an external receptacle R.If the filter 22 is completely emptied of all oil before it is cleanedout, it reduces the possibilities of injuries caused by the hot oil.

An alternative method of emptying the entire oil system is to remove thehousing 22 and then pull out the overflow pipe 32. Thereafter, all ofthe oil in the system will simply run out and fall into a tank 42 whichmay be mounted on wheels 43 for easy removal from the cabinet 20.

FIGS. 3 and 4 show how the filter housing is made, in one exemplaryembodiment of the invention. The principal elements of this filterhousing are a cylindrical, somewhat bucketlike housing 50 having an opentop 53 which may be closed by a cover 54 (FIG. 1 permanently secured tothe bottom of the well 21. Both inlet and outlet pipes (not shown) areconnected through to fittings in the cover 54 to the valve 40 and thepipes 32, 36 of the cooking oil distribution system. Any or all of thesehousing openings and fittings may be sealed in any suitable manner, asby means of rings or gaskets at 55 (FIG. '9). Also, any of these partsmay be flanged and machined to improve the seal. For example, FIG. 3shows a number of bayonets or ears (such as 56) which fit into and lockagainst mating ears or bayonets (not shown) in the cover 54.Thus, whenthe cover 54 is in place on top of the housing 50 and the suitablefittings are secured, the entire unit is sealed to preclude leakage ofhot cooking oil.

A pair of handles 57 on the housing 50 facilitates handling and locking.Thus, it is only necessary to fit the upper edge 56 of the housing 50 upinto the bottom of the top 54 and pull the handles 57 sidewise, thusgiving the bottom 50 a fraction turn and locking it into position.

Means are provided for locking the housing in a closed position so thatit is not possible to open the oil system while filled with hot oil.More particularly, at least one of the bayonets 58 on the top of thehousing 50 has a tab 59 which limits the rotation of the housing when inits closed position. When in the closed position, a suitable key is alsofitted between the bayonet and stop so that the housing cannot beopened.

In greater detail, a handle 65 is located on the front of the housing,as shown in FIG. 1, to control the valve 40. When the handle is in oneposition, the valve 40 is open, the filtration system is in operation,and the housing 22 cannot be opened. When the handle 65 is rotated by90, the valve 40 is closed, the oil is pumped out of the housing 50, andthereafter it may be removed. The light 66 lights when the housing 50 isempty, as signalled when the pump and motor stop after a pretimed cycle.

The top of the housing 22 is seen in outline at 54 (FIG. 5). The bayonet58 and the housing 50 are also shown in outline. A rotatable valve isoutlined at 40. The handle 65 is connected to the valve 40 by a shaft 67having two universal joints 68, 69 therein. Suitable journals 71, 72 areprovided for rotatably supporting this assembly. Therefore, it should beapparent that when the handle 65 is rotated, the valve 40 is opened orclosed. Since the pump 23 runs continuously, all oil is drained out ofthe housing 50 and into the deep well 21 after the valve 40 is closed.

A latch mechanism is shown in detail in FIGS. 6 and 7. This mechanismincludes a support bracket 81 having a cover lock slide 82 mountedthereon. A shaft 83 in the handle-tovalve assembly 67 extends throughthe support bracket 81 and the cover lock slide. The shaft 83 moves acarnlike assembly up and down as the handle is turned. Thus, when thehandle is in one position, the equipment is in the position shown insolid lines in FIG. 7. The lower end of the cover lock 82 interfereswith the stop 59. The housing 50 cannot be removed.

When the handle is rotated, the cam arrangement causes the cover lock 82to move downwardly, as shown in dotted lines at 85. There is nointerference between the cover lock 82 and the stop 59. Therefore, thehandles 57 may be used to rotate the housing 50 so that it will separatefrom the cover 54.

Normally, the housing cannot be removed. When a person using the systemobserves that the lamp 43 is lighted, he knows that the filter needschanging. Then, the person turns the handle 65 to close the valve 40.The pump 23 drains the housing into the well 21. When the hot cookingoil stops flowing followed by the pump and motor shutting off, signal 66lights, and the housing 50 is removed. Excess oil drips into thecontainer 42. If the entire oil system is to be emptied, pipe 32 isremoved and valve 40 is opened by handle 65 with housing 50 removed, andall of the oil runs down into the container. In some embodiments it maybe well to provide a sensor 86 which includes a feeler arm and amicroswitch that operates when the top 54 and the housing 50 are tightlysealed against each other in an operative condition. This switchdisables the motor-pump 23 at any time when the housing is not tightlysealed and may leak. This safety feature also helps to prevent injuriesby burning oil.

Inside the housing 50 is a disposable filterpaper cylinder, bag, orsleeve 90 of porous filter material. The upper end 91 of the cylinder,bag, or sleeve 90 is formed into a cuff or, in the case of the bags,other suitably restricted neck. Mating with and fitting snugly into thisneck is a drainpipe 92. A spring clip 93 fits over the neck 91 and thepipe 92 to hold the filter in place. Initially, the filter cylinder,bag, or sleeve may be shipped in a fully collapsed condition to savespace. Then, after the cylinder, bag, or sleeve is attached to the pipe92,

cooking oil enters and fills it and causes it to expand and bottom onthe housing 59. Thus, the housing 59 and the filter material 911 form apair of concentric, coaxial cylinders when the assembly is put togetherand completely expanded.

To facilitate and enable the assembly of the filter, the drainpipe 92 issealed to the cover 545 in any suitable manner. The outlet 94, whichdischarges the cooking oils from the housing 50, directs it to thedownspouts 38 for allowing the oil to gently flow into the deep well 21.

In one exemplary system, the filter may be melamine treated or polytreated so that edible cooking oils are filtered with the flow of thefluid being 1 to 3 gallons per minute, as follows:

45 lbs. of cooking oil with a temperature range from 275 tocontaminates, food sediments, carbonized particles, odors,

and flavors are strained out Replacement of paper filter occurs when thefiltration is reduced to 70 percent of initial efficiency Porosity-50microns approximately (based on equivalent filter unit rating) Size ofinlet Pipe 92 to Filter 1 inch Size of Outlet Pipe 94 flinch.

The deep frying uses vegetable oils, such as cottonseed, peanut,soybean, corn oils, leaf lards, and the like. Discharge from the deepwell 21 is through the drainpipe 92 and into the cylinder, bag or sleeveof filter material 90. The oil oozes through the filter material 90 tothe inside of the housing 50. The cleanly filtered oil inside thehousing is drawn up the pipe 99 by the action of the motordriven pump23. The oil circulates from the pipe 94! through the pipes 36 and 33 andback to the deep well 21.

An alternative embodiment of the filter arrangement is shown in H6. 10.Here again, there is a top neck 96 which is attached to the drainpipe 92to make a complete filter as sembly. Here, the filter bag has a somewhatparabolic shape flaring from the neck to the bottom.

Yet another embodiment (HS. 11) provides a disposable pleated filterpaper cylinder 97 which is open at both ends and fitted withcompressible rings 99, 99 at each end. These rings seal against the top5 1 and the housing 59 at the bottom, when the unit is assemblied foruse, as in FIG. 11.

The system operates this way. After the well has been cleaned and thescreen 29 is in place, the deep well 21 (FIG. 1) is filled to anindicated level with cooking oil. The heating element 26 is lowered intothe oil. The frying baskets 30, 99 are placed on hangers 31 which may ormay not be equipped to actuate switches and control the power at anylocation in the system where the power should be controlled during acooking cycle.

A switch is operated and the heating element 26 is energized to heat thecooking oil to a thermostatically controlled temperature. A suitablelight 99 may indicate when the oil reaches cooking temperature.

As soon as the oil is hot enough, the drying basket (not shown) isremoved from the hanger 31 and placed in the hot cooking oil. Suitablelights may turn on to indicate that the oil is being filteredcontinuously. When the food is cooked, the basket is again hung on thehanger 31 to drain.

Eventually, the filter material 99 becomes clogged to restrict the flowof cooking oil. As the pump 23 continues to operate, the pressure dropsin the pipe as to actuate the vacuum-sensing switch 41. A light 43lights or another signal occurs.

A person in the area notices the signal and turns the handle 65 to closethe shutoff valve 49 and unlock the housing 22. The motor 23 continuespumping and drains the filter assembly 22 into the deep well 21. Cookingneed not stop. After the pump and motor stop, signal 66 lights; thenhousing 51) may be rotated with the aid of the handles 57 to allow theremoval of the filter. The filter material 90 is removed and replaced.All parts of the housing are cleaned or replaced.

if the oil has been pumped from the deep well 21, the screen 29 isremoved, and the cool oil parts 29 in the well area are cleaned.

From the foregoing, it should be apparent that the invention provides asuperior product by continuously filtering cooking oil whenever aproduct is being cooked. However, if should also be recognized thatother structures could be made without departing from the teachings ofthe invention. Accordingly, the appended claims should be construed tocover all equivalents reasonably falling within the scope and spirit ofthe invention.

1 claim:

1. A food fryer comprising means including a deep well for receiving andheating food and cooking oil, means for continuously filtering said oilthroughout cooking, said filtering means comprising a screen means insaid deep well for supporting food while allowing larger particles tosettle out of said cooking oil, means above the level of said screen forpumping oil into and out of a chamber of porous filter material, saidoil oozing through pores in said filter material whereby the pressure ofpumped oil changes responsive to a clogg'ng of said filter material, andmeans responsive to said changed pressure for indicating the cloggedcondition of said filter.

2. The fryer of claim 1 wherein said straining means comprises aperforated member which divides the deep well into two parts, one ofsaid two parts forming a cooking chamber, the other of said two partsforming a cool oil chamber for accumulating sediment which has settledout of said oil and fal len through said perforated member.

3. The fryer of claim 1 and means for returning said oil to said deepwell without washing said food with a fast flowing current of oil.

1. The fryer of claim 1 wherein said filtering means comprises a seriesof pipes for conducting said oil from said deep well through saidfiltering means and back to said well, and a shutoff valve between anoutlet of said deep well and an inlet of said filtering means, saidpumping means being in said pipe between the outlet of said filter andthe inlet of said deep well, whereby said pump empties said filteringmeans into said deep well when said shutoff valve is closed.

9. The fryer of claim 1 wherein said pumping means is coupled to anoutlet of said filtering means, said means responsive to said changedpressure comprising a vacuum sensor coupled between an outlet from saidfilter and said pumping means.

is. A deep fat fryer comprising a deep well having a bottom with a draintherein, housing means comprising a cover directly connected to saiddrain, a bucketlike means having an open top fitting into said cover,clamp means for selectively attaching or detaching said bucketlike meansto said cover, filter means comprising a tubular sleeve of porousmaterial resting in said bucketlike member and compressed against saidcover when said clamp means is operated, and means for pumping cookingoil from said bucket member back into said well, said drain dischargingoil from said well on one side of said filter material and said pumpsucking oil from the other side of said material, whereby said oil mustpass through said filter as said oil moves between said drain and saidpump.

7. A deep fat fryer comprising a deep well for receiving cooking oil andfood to be cooked, a filter assembly beneath said deep well, oilcirculating means including a motor-pump assembly for circulating oilfrom said deep well through said filter assembly and returning said oilto said deep well without causing fast-flowing currents in said oil,wherein said filter assembly comprises a housing having an inlet andoutlet for enabling the flow of oil through said housing, and a sleeveof porous filter material interposed between said inlet and outlet sothat oil must ooze through the pores of said filter material in order topass from said inlet to said outlet, wherein said filter material is apleated filter paper bag which clips onto the inlet of said housing.

8. The fryer of claim 7 and means for locking said housing in a closedcondition if said housing has hot cooking oil therein.

9. The fryer of claim 8 and means for settling said cooking oil beforesaid oil enters said filter material, thereby precluding entry of largeparticles into said filter paper bag.

10. A deep-fat food fryer comprising a deep well with an outlet, saidwell comprising means for receiving cooking oil and food to be cooked insaid oil, means in said well for heating said oil to the range of 275 to400 F., and filter means comprising a bag of filter material, the top ofsaid bag being attached to said outlet of said well, said bag beingcircumferentially pleated to collapse said bag vertically for shipmentand storage and to expand said bag responsive to flow of said oil fromsaid deep well and into said filter bag.

11. The fryer of claim 10 wherein said bag is of cylindrical shape whenexpanded.

12. The fryer of claim 10 wherein said bag has a generally paraboliccross section flaring from the point where said bag is attached to saidwell to the bottom of the bag.

13. The fryer of claim 12 wherein said bag is made of paper having aporosity of 40 to 65 microns.

14. The fryer of claim 13 wherein said paper is treated with melamine.

15. A deep fat fryer comprising a deep well for receiving cooking oil,said well having a deflector means extending along at least a part ofits peripheral wall, means comprising a porous filter for filteringcooking oil during a cooking cycle, a down spout positioned to dischargecooking oil onto said deflector means, thereby precluding swift currentsin the cooking oil in said well, and pump means for pumping oil fromsaid well, through said porous filter, and back into said well via saiddown spout, whereby said oil is filtered continuously during cooking andreturned to said well with a gentle flow of oil which does not wash ordisturb the food in said well.

16. The fryer of claim 15 wherein means associated with said fryercomprising a filter housing which is formed to open or close, saidfilter assembly is a disposable pleated filter paper having compressiblerings at each end thereof, and said rings are sealed against theopposite sides of said housing when said housing is in a closedcondition.

17. A deep-fat fryer comprising a deep well having a drain leading to afilter housing, said filter housing comprising a cover having bayonetears distributed around the periphery thereof and a bucketlike memberhaving mating bayonet ears which interlock with the bayonet ears on saidcover when the bayonet ears on said bucketlike member are fitted intosaid cover and rotated slightly, filter means comprising a tubularsleeve of porous material resting in said bucketlike member andcompressed against said cover when said bucket member is rotated andsaid bayonet ears are interlocked, and means for pumping cooking oilfrom said bucket member back into said well, said drain discharging oilfrom said well on one side of said filter material and said pump suckingoil from the other side of said material, whereby said oil must passthrough said filter as said oil moves between said drain and said pump.

18. The fryer of claim 17 and means for locking said housing in a closedcondition if said housing has hot cooking oil therein.

19. The fryer of claim 17 wherein said porous material is paper having aporosity of 40 to 65 microns.

20. The fryer of claim 19 wherein said paper is treated with melamine.

1. A food fryer comprising means including a deep well for receiving andheating food and cooking oil, means for continuously filtering said oilthroughout cooking, said filtering means comprising a screen means insaid deep well for supporting food while allowing larger particles tosettle out of said cooking oil, means above the level of said screen forpumping oil into and out of a chamber of porous filter material, saidoil oozing through pores in said filter material whereby the pressure ofpumped oil changes responsive to a clogging of said filter material, andmeans responsive to said changed pressure for indicating the cloggedcondition of said filter.
 2. The fryer of claim 1 wherein said strainingmeans comprises a perforated member which divides the deep well into twoparts, one of said two parts forming a cooking chamber, the other ofsaid two parts forming a cool oil chamber for accumulating sedimentwhich has settled out of said oil and fallen through said perforatedmember.
 3. The fryer of claim 1 and means for returning said oil to saiddeep well without washing said food with a fast flowing current of oil.4. The fryer of claim 1 wherein said filtering Means comprises a seriesof pipes for conducting said oil from said deep well through saidfiltering means and back to said well, and a shutoff valve between anoutlet of said deep well and an inlet of said filtering means, saidpumping means being in said pipe between the outlet of said filter andthe inlet of said deep well, whereby said pump empties said filteringmeans into said deep well when said shutoff valve is closed.
 5. Thefryer of claim 1 wherein said pumping means is coupled to an outlet ofsaid filtering means, said means responsive to said changed pressurecomprising a vacuum sensor coupled between an outlet from said filterand said pumping means.
 6. A deep fat fryer comprising a deep wellhaving a bottom with a drain therein, housing means comprising a coverdirectly connected to said drain, a bucketlike means having an open topfitting into said cover, clamp means for selectively attaching ordetaching said bucketlike means to said cover, filter means comprising atubular sleeve of porous material resting in said bucketlike member andcompressed against said cover when said clamp means is operated, andmeans for pumping cooking oil from said bucket member back into saidwell, said drain discharging oil from said well on one side of saidfilter material and said pump sucking oil from the other side of saidmaterial, whereby said oil must pass through said filter as said oilmoves between said drain and said pump.
 7. A deep fat fryer comprising adeep well for receiving cooking oil and food to be cooked, a filterassembly beneath said deep well, oil circulating means including amotor-pump assembly for circulating oil from said deep well through saidfilter assembly and returning said oil to said deep well without causingfast-flowing currents in said oil, wherein said filter assemblycomprises a housing having an inlet and outlet for enabling the flow ofoil through said housing, and a sleeve of porous filter materialinterposed between said inlet and outlet so that oil must ooze throughthe pores of said filter material in order to pass from said inlet tosaid outlet, wherein said filter material is a pleated filter paper bagwhich clips onto the inlet of said housing.
 8. The fryer of claim 7 andmeans for locking said housing in a closed condition if said housing hashot cooking oil therein.
 9. The fryer of claim 8 and means for settlingsaid cooking oil before said oil enters said filter material, therebyprecluding entry of large particles into said filter paper bag.
 10. Adeep-fat food fryer comprising a deep well with an outlet, said wellcomprising means for receiving cooking oil and food to be cooked in saidoil, means in said well for heating said oil to the range of 275* to400* F., and filter means comprising a bag of filter material, the topof said bag being attached to said outlet of said well, said bag beingcircumferentially pleated to collapse said bag vertically for shipmentand storage and to expand said bag responsive to flow of said oil fromsaid deep well and into said filter bag.
 11. The fryer of claim 10wherein said bag is of cylindrical shape when expanded.
 12. The fryer ofclaim 10 wherein said bag has a generally parabolic cross sectionflaring from the point where said bag is attached to said well to thebottom of the bag.
 13. The fryer of claim 12 wherein said bag is made ofpaper having a porosity of 40 to 65 microns.
 14. The fryer of claim 13wherein said paper is treated with melamine.
 15. A deep fat fryercomprising a deep well for receiving cooking oil, said well having adeflector means extending along at least a part of its peripheral wall,means comprising a porous filter for filtering cooking oil during acooking cycle, a down spout positioned to discharge cooking oil ontosaid deflector means, thereby precluding swift currents in the cookingoil in said well, and pump means for pumping oil from said well, throughsaid porous filter, and back inTo said well via said down spout, wherebysaid oil is filtered continuously during cooking and returned to saidwell with a gentle flow of oil which does not wash or disturb the foodin said well.
 16. The fryer of claim 15 wherein means associated withsaid fryer comprising a filter housing which is formed to open or close,said filter assembly is a disposable pleated filter paper havingcompressible rings at each end thereof, and said rings are sealedagainst the opposite sides of said housing when said housing is in aclosed condition.
 17. A deep-fat fryer comprising a deep well having adrain leading to a filter housing, said filter housing comprising acover having bayonet ears distributed around the periphery thereof and abucketlike member having mating bayonet ears which interlock with thebayonet ears on said cover when the bayonet ears on said bucketlikemember are fitted into said cover and rotated slightly, filter meanscomprising a tubular sleeve of porous material resting in saidbucketlike member and compressed against said cover when said bucketmember is rotated and said bayonet ears are interlocked, and means forpumping cooking oil from said bucket member back into said well, saiddrain discharging oil from said well on one side of said filter materialand said pump sucking oil from the other side of said material, wherebysaid oil must pass through said filter as said oil moves between saiddrain and said pump.
 18. The fryer of claim 17 and means for lockingsaid housing in a closed condition if said housing has hot cooking oiltherein.
 19. The fryer of claim 17 wherein said porous material is paperhaving a porosity of 40 to 65 microns.
 20. The fryer of claim 19 whereinsaid paper is treated with melamine.